The present invention relates to an elevator, particularly for transporting persons, which comprises an elevator shaft, an elevator car guided in the elevator shaft and a drive motor directly driving the elevator car. The drive motor is provided with an active primary part arranged at the elevator car and a passive secondary part arranged in stationary position in the elevator shaft and spaced from the primary part by an air gap.
The elevator car of conventional elevators is usually moved up and down in the elevator shaft by means of wire cables that run over a drive pulley driven by an electric motor. This indirect drive of the elevator car is associated with the disadvantage of an additional space requirement for the drive pulley and the electric motor.
In addition, elevators that are provided with a direct drive of the elevator car are known in the state of the art. Thus, the European patent document EP 0 785 162 A1 describes an elevator in which the elevator car is driven directly by a linear motor. The linear motor comprises a primary part arranged at the elevator car and a secondary part fastened to the wall of the elevator shaft and provided with permanent magnets. The primary part is provided with windings to which a three-phase current is supplied. In this manner there is created a magnetic traveling field forming electromagnetic forces which linearly move the primary part and thus the elevator car relative to the secondary part.
A linear motor directly driving the elevator car is additionally known from the European patent document EP 0 858 965 A1. With respect to low transverse forces, this linear motor has a secondary part which is arranged at the elevator car and which is formed from two rows of mutually opposite permanent magnets. The primary part, thereagainst, consists of windings that are arranged between the permanent magnets of the secondary part.
The provision of a linear motor for direct drive of the elevator car does indeed have the advantage, in distinction from elevators with an indirect drive by means of cables, that no additional space requirement for an electric motor and a drive pulley is needed. Moreover, the provision of a linear motor makes a counterweight connected with the elevator car redundant. An insufficient power capability and a manufacturing cost that is comparatively high in the economic respect have proved to be disadvantages of the known linear motors particularly in the case of relatively high elevator shafts. With respect to manufacturing cost, it is possibly required to provide the entire wall of the elevator shaft with either the secondary part or the primary part. Since the primary part comprises several windings and the secondary part is equipped with permanent magnets, comparatively high costs thus result.